1. Field of the Invention
High-pressure gaseous oxygen is typically utilized as the oxidizer in the bipropellant systems of many spacecraft. In many of these systems, gaseous oxygen at high pressures are often heated to elevated temperatures of 500-degrees or more before the oxidizer is introduced at a selected flow rate into the combustion chamber of the spacecraft engine.
The invention relates to new and improved flow regulating devices for high-pressure gases that are flowing at extreme temperatures. More particularly, the present invention is directed to new and improved apparatus for regulating the flow of gases such as a high-pressure gaseous oxygen at elevated temperatures as these gases are being discharged into the combustion chamber of a spacecraft rocket engine.
2. Background Art
The typical flow control valve is arranged for regulating the flow of various gases or liquids in a predictable manner over a selected range of flow conditions and pressures and temperatures. With some types of control valves, it is also preferred to arrange the flow passages through those valves to minimize disruptions or significant turbulence of those fluids which are passing through the valves. Generally, little consideration is given to the nature of the fluids which are to be regulated by a particular flow control valve unless those fluids are corrosive (e.g., an acid or a strong caustic) or the fluids are abrasive (e.g., a slurry of fine particulates such as carbon black or coal). It will, of course, be appreciated that in most situations, specialized fluids are readily accommodated either by fabricating the critical components of the regulator valves from appropriate plastics, ceramics or metals or by protecting the exposed surfaces of these components with suitable materials.
Heretofore there has been only a limited demand for flow control devices which are capable of regulating the flow of fluids such as gaseous oxygen at elevated temperatures and pressures. Accordingly, the critical problems of regulating such fluids have not been widely addressed heretofore. As a result, the large majority of the prior-art control valves are generally not suited for controlling these specialized fluids. Therefore, it was not until the advent of rocket propulsion systems that utilize gaseous bipropellants that it became essential to provide flow regulators capable of controlling fluids of such a specialized nature.
In particular, those skilled in the art will appreciate that where a critical fluid such as gaseous oxygen at a high pressure and elevated temperature is to be controlled, the control valve must be carefully designed to minimize the risk of violent combustion of the gas passing through the valve. For instance, where a control valve has a tortuous flow passage, there is always a pronounced risk that gaseous oxygen flowing at high velocities through the valve may be spontaneously ignited by the impact of the gas against flat surfaces or corners present in the flow passage. Moreover, it has been found that the risk of spontaneous combustion is significantly increased by the presence of a few extremely-small metal particles in a high-velocity stream of gaseous oxygen that is flowing through a control valve which has only a modest transition zone or a minor change of direction in its flow passage. Tests have shown, for example, that when even a small number of metal particles which are no larger than 2,000-.mu.m (0.079-inch) are inadvertently being transported in a high-velocity stream of oxygen, the impact of those particles against metal surfaces within the valve can promote the combustion of the surrounding materials. Thus, since it is substantially impossible to completely eliminate the presence of such minute particles in the flow lines and propellant tanks in the main propulsion system of a bipropellant rocket engine, it is essential that every component in the system be designed to minimize as far as possible the risk that the impact of one or more of these particles against some metal surface in the system will cause a violent combustion in the system.